In modern internal combustion engines, devices for varying the timing of gas exchange valves are used to enable the phase relation between the crankshaft and the camshaft to be configured in a variable manner within a defined angular range, between a maximum advance and a maximum retardation position. For this purpose, the device is integrated into a drive train, via which a torque is transmitted from the crankshaft to the camshaft. This drive train can be embodied as a belt, chain or gearwheel drive, for example. Such a device generally comprises an output element (rotor), which is arranged so as to be rotatable relative to an input element (stator), wherein the stator is in driven connection with the crankshaft and the rotor is connected to the camshaft for conjoint rotation.
According to DE 10 2009 005 114 A1, the concentric arrangement of the stator and the rotor is bounded axially by two cover disks. The stator, the rotor and the two cover disks bound a plurality of pressure spaces, each of the pressure spaces being divided into two oppositely acting pressure chambers by means of a vane. By supplying pressure medium and discharging pressure medium to and from the pressure chambers, the vanes are moved within the pressure spaces, thereby bringing about a specific rotation of the rotor relative to the stator and thus of the camshaft relative to the crankshaft.
In order to move the rotor back into a rest or initial position relative to the stator, springs are sometimes also used. Flat spiral torsion springs are often used, typically being secured on the rotor and on the stator by means of pins or screws.
To ensure that the spring does not jump out of the holder provided during operation, a spring cover is provided to fix the spring. In DE 10 2009 005 114 A1, the spring is arranged between the spring cover and a front cover disk, wherein a plurality of bolts pass through the spring cover, the front cover disk, the stator and the rear cover disk. Depending on costs and function, spring covers are predominantly manufactured from steel sheet or from plastic. In order to be able to perform their function, it is particularly important that they do not come away from the device under the operating loads which occur.